Current Concepts in MR and CT Arthrography

As techniques in orthopedic surgery and, specifically, arthroscopic surgery continue to advance, the demands of patients and surgeons regarding preoperative diagnosis, preoperative planning, and preoperative patient counseling continue to increase. Fortunately, medical imaging continues to advance and improve and thus match many of the demands and expectations of surgeons and patients. Most recently, advances in MR imaging such as higher field magnets, stronger and faster gradients, more robust coil designs, and more efficient sequences have significantly improved imaging of the musculoskeletal system. In some cases, such improvements have resulted in sufficient spatial and contrast resolution so as to obviate the need for arthrography prior to MR imaging. In addition, advances in CT including tube, detector, and software modifications have significantly improved CT image quality and the amount of information that can be obtained. However, despite these improvements, MR arthrography and CT arthrography remain relevant in specific clinical scenarios. The current issue of Seminars in Musculoskeletal Radiology is thus dedicated to MR and CT arthrography with an emphasis on the clinical relevance and indications of these techniques in both academic and private settings. The articles represent the viewpoints and experience from experts in both North America and Europe. Each article reviews the indications, techniques, relevant anatomy, and common pathological conditions that can be encountered at CT/MR arthrography.

Dr. Rhee and colleagues lead the way with an in-depth and detailed discussion of the techniques and indications for MR arthrography of the shoulder, one of the most common joints to be imaged both with conventional and arthrographic MR. Included are tips regarding injection techniques, protocols, variants of anatomy that may simulate disease, and common and uncommon pathology. This comprehensive article should serve as an excellent resource for both novice and experienced radiologists who must perform and interpret this common examination.

The next article, written by Drs. Delport and Zoga, addresses the indications and challenges associated with CT/MR arthrography of the elbow, one of the less common joints studied in most centers. In general, with appropriate protocols, the elbow can be imaged with nonarthrographic cross-sectional imaging and with ultrasound. However, as indicated in the article, there are specific scenarios, including but not limited to professional athletes, where arthrography prior to CT/MR imaging is desired and oftentimes required to make an accurate and timely diagnosis.

The last upper extremity article, by Dr. Cerezal and colleagues, covers the indications, techniques, and detailed anatomy and pathology of the wrist. Given the recent advances in wrist arthroscopic techniques, it has become evident that in many cases the smaller intrinsic ligaments that were previously either poorly seen or not seen by nonarthrographic imaging techniques are very relevant in determining surgical approach. As such, this article should be of particular interest to those readers working in settings where wrist arthroscopy is performed.

Dr. Llopis and colleagues take on the task of addressing one of the hottest topics: internal derangement of the hip. The incredible interest in hip arthroscopy over the past 10 years, much of which is due to the recognition of the concept of femoroacetabular impingement, has made hip CT/MR arthrography an extremely common examination in private and academic centers around the world. As such, surgeons are requesting more detailed information regarding the preoperative status of the osseous anatomy, acetabular labrum, and the cartilage. In addition to the better known techniques, Dr. Llopis and colleagues also review some of the advantages of combined CT/MR arthrography as well as the use of leg traction during MR arthrography to address the surgeons' requests.

Finally, Drs. Kalke, Di Primio, and Schweitzer describe the current indications and techniques for CT/MR arthrography of the knee. Although advances in coil design and protocol design often allow internal derangement of the knee to be adequately assessed with nonarthrographic imaging, the authors review and demonstrate the current indications, utility, and necessity of arthrography in both pre- and postoperative settings including in the assessment of articular cartilage.

Unfortunately, due to circumstances beyond our control, the ankle joint is not covered in this issue. We hope it will be covered in a future issue of Seminars.

Finally, I would like to thank the editors for giving me the opportunity to serve as guest editor for this issue. In addition, I would like to sincerely thank all the authors for their excellent contributions to this issue that I believe will be of great interest to all readers and will also serve as a go-to guide in many departments because it covers indications, techniques, and pathologies in a succinct, relevant, and accessible manner.